What sort of tools would we need to connect the sky to the earth?
Getting to space is an incredible hassle. Rockets need to be designed, built, and tested to the extreme in order to verify their readiness. They then have to be filled almost entirely with fuel, leaving only small spaces for cargo and people to be brought to space. Not to mention, the journey itself is filled with innumerable dangers and potential malfunctions. But what if there was a way to circumvent all of these problems? What if there was a feat of engineering so powerful that it would not require any fuel or any rockets to get to space? What if you could bring thousands of people and tons of cargo to and from orbit with no struggle?
Enter the space elevator. This proposed work of engineering involves creating a cable that would stretch from the surface of a planet to space. One end of the cable would be tethered to the ground, while the other end would have a counterweight built around it. As the planet spins, the counterweight would be pulled outward by centrifugal force, holding the immense cable rigid (1). Elevators as large as buildings could then run up and down the cable, seamlessly transferring people and cargo to and from orbit (1). That may sound like the perfect way to increase access to space. However, along with the elevator’s numerous benefits come some of the hardest engineering problems that humans could ever face. For example, how would engineers even go about manufacturing a cable that is tough enough to remain intact as it stretches for tens of thousands of kilometers? Where would they find the materials for a space elevator? How and where would it be built? How long would construction take? The science fiction epic Red Mars by Kim Stanley Robinson answers all of these questions as it details a plausible way that a space elevator could go from concept to reality.
In the novel, a space elevator is built to connect Mars with an asteroid above the planet. The first two problems that are tackled are the elevator’s construction location and the sourcing of its materials. After all, it is impossible to start building the elevator cable on Mars, because there is no way to get that much weight up into orbit to connect to the counterweight. Furthermore, the logistical challenges involved with sourcing any needed materials are immense: the cable material either has to be mined from the Martian surface or brought from Earth, both of which incur eye-watering costs. Thus, the elevator designers decide to start the construction from the counterweight. That way, the cable can be manufactured in orbit, and Mars’ gravity will do all the work of pulling it down to the planet. By using a metal-rich asteroid as the counterweight, the designers also solve the issue of sourcing materials, since the substances needed for cable construction are readily available. After an Amor (near-Earth) asteroid is maneuvered into Martian orbit, the elevator’s construction can begin (2, 3).
The third problem addressed with the space elevator is the design and manufacturing of the cable itself. In the book, the elevator designers settle on carbon nanotubes for the cable material. Carbon nanotubes are a real material used today, and they possess the highest tensile strength (ability to withstand pulling forces) of any known material, making them the perfect component for keeping a thirty-seven thousand kilometer long elevator together (2, 4). But the amount of nanotube needed is unimaginable, and having humans work to mine and manufacture the material is simply not feasible. Therefore, the designers turn to another powerful engineering concept: self-replicating autonomous factories. These factories are able to monitor their own needs while also managing armies of mining and manufacturing robots. In addition, each factory has the capability to build other factories. Thus, to begin the elevator’s construction, the designers place just a few factories on the asteroid. These initial factories mine parts of the asteroid in order to construct the rest of the needed factories, and once the asteroid is covered in one massive factory, all attention is devoted to the cable. Without a single bit of human intervention, the six-billion ton elevator cable is produced in eleven years and then gracefully lowered onto the Martian surface (2).
So, what lessons for real-life space elevators can we draw from Red Mars? Well, we know that space elevators are theoretically possible to build, but the main difference between our world and Red Mars’ is the scale of resources available. If we were to undertake such an endeavor today, we would need large-scale autonomous factories, not to mention already-established space infrastructure to find and maneuver an asteroid into a desired position. These are massive hurdles of their own which may not be overcome for decades to come. But these challenges are not impossible to surmount. Once humans are able to take the first steps towards engineering on a truly huge scale, we may see tethers on the horizon, reaching for skies beyond.
Bibliography
- N/A. (2014). What is a Space Elevator? International Space Elevator Consortium. Retrieved from https://www.isec.org/faq/#What%20is%20it
- N/A. (2023). Space Elevator. KimStanleyRobinson.info. Retrieved from https://www.kimstanleyrobinson.info/content/space-elevator#:~:text=An%20Amor%20asteroid%20was%20used,thick%2C%20weighing%206%20billion%20tons.
- Baalke, R. (2002, February 2). Near-Earth Object Groups. NASA. Retrieved from https://web.archive.org/web/20020202160655/http://neo.jpl.nasa.gov/neo/groups.html
- Ren. G. (2016, August 5). Carbon Nanotube. Encyclopedia Britannica. Retrieved from https://www.britannica.com/science/carbon-nanotube
Images
- Wikipedia Contributors. (2024, March 30). Space elevator. Wikipedia. Retrieved from. https://en.wikipedia.org/wiki/Space_elevator
- Snowden, S. (2018, October 2). A colossal elevator to space could be going up sooner than you ever imagined. NBC News. Retrieved from https://www.nbcnews.com/mach/science/colossal-elevator-space-could-be-going-sooner-you-ever-imagined-ncna915421